The present invention relates generally to the field of batteries and deals more specifically with a battery system, and more particularly with a battery pack and a related battery pack engagement and holding arrangement for portable handheld and mobile electronic devices such as a mobile cellular telephone.
Consumers continue to demand that mobile electronic devices such as mobile cellular telephones be lighter, smaller and thinner and to provide additional communication features and capabilities. In order to meet the demands of consumers, higher capacity and increased energy density rechargeable batteries are required. Although great advances have been made in battery technology to increase energy density such as, for example, lithium ion, within a given available space, a number of factors related to the battery pack construction and form and the electronic circuitry required to utilize such battery packs imposes limits on the energy density attainable within the given space. Typically, a mobile phone battery pack includes an individual battery cell that provides the electrical power via lead plates or wires or conductors that are used to connect the cell to a protection circuit and/or a protection device. The protection circuit functions to protect not only the user, but also the battery cell and the mobile phone from damage in the event of misuse or a malfunction.
The protection circuits inside the battery pack function to prevent or limit over-voltage charging, under-voltage discharging, high discharge currents and high charge currents and/or high temperature operating conditions. These additional and typically separate protective functions are necessary because the battery cell, such as a lithium ion battery cell, cannot by itself provide these functional safety requirements without the protection circuits. Generally, the protection circuit electronic components are mounted on a printed circuit board of some type which is also contained within the battery pack. Additionally, plastics or foils may be used to provide mechanical durability and to prevent electrical shorts between the cell and other components of the battery pack including the battery pack itself.
The requirement for such protection circuitry and other protective devices within the battery pack adds to the cost of the mobile cellular telephone battery pack and it is estimated that 50% of a battery pack cost is other than the battery cell itself. Additionally, the space requirements for such protection circuitry and devices consumes space which might otherwise be available to the battery cell to increase within a given space the energy density of the battery pack used with the mobile cellular telephone.
There is a need therefore to provide a battery pack for use with a mobile cellular telephone that provides increased energy density by accommodating a larger battery cell within a given space and in which protection devices are not contained within the battery pack to maximize volume for the battery cell. There is also a need for a related battery pack engagement and holding arrangement for use with the mobile telephone that facilitates easy insertion and removal of the battery pack. The present invention satisfies these needs, as well as others, and generally overcomes the problems and deficiencies associated with known preformed and molded battery packs used with mobile telephones.
An object of the present invention is to provide a battery pack and a related battery pack engagement and holding arrangement for use in a mobile cellular telephone.
Another object of the invention is to locate a battery cell protective device exterior of the interior portion of the battery pack structure carrying the battery cell.
A further object of the invention is to provide a battery pack engagement and holding arrangement for use with the mobile cellular telephone in which the battery pack is easily inserted and removed from the mobile cellular telephone.
A yet further object of the invention is to provide a battery pack for use with a mobile cellular telephone that includes a weaken wall area to relieve excessive pressure build-up within the battery pack.
In accordance with the invention, a battery system for use in a portable electronic device is presented. A shallow profile, axially elongated thin wall can structure having a width, height, axial length and shape corresponding generally to the width, height, axial length and shape, respectively of the battery package receiving and holding region of the electronic device. The can structure has an opening at one end for receiving and holding anode and cathode material and electrolyte defining a battery cell. A safety component is electrically coupled between one of the anode or cathode means and a first voltage potential output contact means. The other of the anode and cathode means is electrically coupled to a second voltage potential output contact means. The safety component is carried by insulating means having a size and shape corresponding to the opening of the can structure to cover the opening. A cap has an outer peripheral surface size and shape corresponding to the size and shape of the can structure at one end and is coextensive with the outer surface of the can structure for sealing the opening. The cap has an outwardly extending flange region for engagement with holding means located at one end portion of the battery package receiving and holding region of the electronic device when the battery package is in its operative position within the device. Means for releasing the battery package from its operative position within the device is formed in the outer wall of the can structure at the end opposite the opening.
Preferably, the insulating means further comprises a first insulating plate and a second insulating plate in a facing relationship with one another to sandwich the safety component therebetween.
Preferably, the cap is attached and held the to the first insulating plate.
Preferably, a rivet has a head and body wherein the body passes through one end of the safety component, through the first insulating plate and through the cap to hold the safety component, first insulating plate and the cap together.
Preferably, the rivet body and head are hollow and define a conduit between the end located at the cap and the head located adjacent the second insulating plate. The second insulating plate has an aperture therethrough and in alignment with and communication with the rivet head for carrying electrolyte from the rivet end through the rivet body and the rivet head into the interior of the can structure and into contact with the anode and cathode material.
Preferably, means seal the rivet body end to prevent electrolyte from escaping from the battery package.
Preferably, an electrically non-conductive coating is applied to the exterior surface of the battery package.
Preferably, the non-conductive coating further comprises a sleeve for covering the surface of the battery pack.
Preferably, the releasing means further comprises a finger groove in the outer surface of the end wall.
Preferably, the wall thickness of the finger groove is selected to rupture upon pressure build-up inside the battery package to prevent the battery package from exploding.